1. Field of the Invention
The present invention relates to a ground terminal, and more particularly, to a ground terminal mounted on a printed board for establishing an electrical connection between a printed board ground and a chassis ground of an electronic device.
2. Description of the Prior Art
In the case of mounting a printed board to an electronic device, the printed board is generally to be grounded. To this end, conventionally, a printed board ground is electrically connected with a chassis ground of the electronic device with use of a ground wire, for instance. In this case, after the printed board is installed on the chassis, opposite ends of the ground wire must be soldered to the printed board ground and the chassis ground, or one end of the ground wire whose other end is soldered beforehand to the printed board ground must be soldered to the chassis ground. However, the soldering work requires much labor.
To obviate this, it has been known to mount, on a printed board, a ground terminal for establishing electrical connection between a printed board ground and a chassis ground, to thereby eliminate the need for soldering work.
As shown in FIG. 1, a conventional ground terminal 2 typically includes a terminal body 2a, and leads 2b, 2c and 2d which are integrally formed with the terminal body 2a. When the ground terminal 2 is installed on a printed board 1, the leads 2b, 2c and 2d are inserted into holes 1a formed in the printed board 1, and are soldered to a grounding land (not shown) formed in the rear surface of the printed board 1. Next, the ground terminal 2 is bent at nearly right angles at a boundary between the terminal body 2a and the leads 2b to 2d, so that the ground terminal 2 extends along the printed board 1, as shown in FIG. 2. As a result, most parts of the terminal body 2a are disposed at a location outside the printed board 1. When the printed board 1 is built in the electronic device, the printed board 1 is disposed at a location adjacent to a chassis ground 3, so that a screw insertion hole 2e formed in the outer end portion of the ground terminal 2 located outside the printed board 1 is in alignment with a screw hole 3a formed in the chassis ground 3. Then, a screw, loosely received in the screw insertion hole 2e of the ground terminal 2, is threadably engaged with the screw hole 3a of the chassis ground 3, and is then fastened. Whereby the ground terminal body 2a is fixed to the chassis ground 3, so that the printed board 1 is electrically and mechanically connected to the chassis ground through the ground terminal 2.
In another example of installation shown in FIG. 4, the leads (one of which is shown by reference numeral 2c) of the ground terminal 2 are received in the printed board 1 and are soldered to the grounding land 1b of the printed board, as in the case of FIG. 2. As distinct from the installation example shown in FIG. 2, however, the entirety of the ground terminal 2 is disposed on the upper surface 1c of the printed board 1. In this respect, the printed board 1 is formed with a hole 1d which extends through the printed board 1 and which receives the screw 4. Further, the chassis ground 3 is disposed below the printed board 1. With regard to other respects, the installation example of FIG. 4 is the same as that shown in FIG. 2, so that the printed board 1 is grounded to the chassis through the ground terminal 2 by fastening the ground terminal 2, mounted to the printed board 1, to the chassis by means of the screw 4.
The soldering work conventionally required upon installation of the printed board 1 onto the electronic equipment or the like can be eliminated by disposing the ground terminal 2 shown in FIG. 1 between the printed board and the chassis, as shown in FIG. 2 or FIG. 4. This makes it possible to improve installation efficiency.
However, since the ground terminal 2 is comprised of a thin plate and is fixed to the printed board 1 through the fine leads 2b to 2d, the ground terminal 2 can be deformed when it receives a fastening force when the ground terminal 2 is fastened to the chassis with use of the screw 4. Namely, the ground terminal body 2a can be bent, or the leads 2b to 2d can be twisted.
Further, if dust, oil film or the like is adhered to opposite surfaces of the ground terminal body 2a and the chassis ground 3, these elements 2a and 3 which are subsequently caused to be in contact with each other are electrically insulated by the dust or the like, so that a defective electrical connection can be established between the terminal body 2a and the chassis ground 3.
Moreover, as shown in FIGS. 1 and 3, the conventional ground terminal 2 is cut at right angles at its corners 2f of those portions at which the terminal body 2a is combined with the opposite leads 2b and 2d. Thus, the corners 2f of the ground terminal 2 can be brought in contact with the upper surface of the printed board 1 when the ground terminal 2 is bent along the upper surface of the printed board 1 as mentioned above, so that the surface of the printed board 1 is injured. In this case, the appearance of the printed board 1 is deteriorated. Further, in the case of a double-sided printed board, a land (conductor pattern) formed in the upper surface of the board can be injured or cut off.